Concentration dependence of energy transfer between Eu3+ ions occupying two symmetry sites in Lu2O3
Concentration dependence of energy transfer between Eu3+ ions occupying two symmetry sites in Lu2O3
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DOI：
10.1088/0953-8984/14/22/315
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发表时间：
2002-05
期刊：
影响因子：
--
通讯作者：
E. Zych
中科院分区：
文献类型：
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作者：
E. Zych
以烧结片剂的形式制备了一系列掺Eu的Lu2O3样品。活化剂浓度分别为Lu的0.2、1、3、5、7、10%。在液氮和室温条件下，用不同能量的光激发了发射光谱。还记录了Lu2O3 （C2和S6）中两个不同对称位的特征Eu发射谱线的激发光谱。结果表明，位于两个不同对称位的Eu离子在7F0→5D1吸收区和电荷转移跃迁区均具有特征激发谱。在这两种情况下，Eu（S6）离子的水平都高于Eu（C2）。在发射光谱和激发光谱中都观察到能量从占据Lu2O3中心对称S6位的Eu离子转移到非中心对称C2位的Eu离子。一些迹象表明，反向转移（从C2的Eu到S6位点的Eu）也发生了。较低的温度显著降低了Eu（S6）→Eu（C2）的转移速率。衰变动力学表明，即使在室温下，如果掺杂量大于10%，则Eu（S6）的发射量也会进一步降低。在室温和液氮温度下，所有浓度下Eu（C2）排放物的衰变动力学特征为时间常数约为1.0 ms，表明高达10%的掺杂量没有发生浓度或热猝灭。液氮Eu（S6）在0.2%样品中的发光时间常数约为7 ms。在室温下，这个值降低到5.6毫秒。
A series of Lu2O3 samples doped with Eu was prepared in the form of sintered tablets. The activator concentration was 0.2, 1, 3, 5, 7 and 10% with respect to Lu. Emission spectra excited with light of various energies were taken at liquid nitrogen and room temperature. Excitation spectra of characteristic Eu emission lines for two different symmetry sites in Lu2O3 (C2 and S6) were also recorded. It was shown that Eu ions located in the two different symmetry sites possess characteristic excitation spectra in the regions both of the 7F0→5D1 absorption and of the charge transfer transitions. In both cases the levels of the Eu(S6) ions were located above those of the Eu(C2). In both emission and excitation spectra an energy transfer from Eu ions occupying the centrosymmetric S6 site in Lu2O3 to Eu ions in the noncentrosymmetric C2 site was observed. Some indications were found that an opposite back-transfer (from Eu in C2 to Eu in the S6 site) also occurs. Lower temperature significantly reduces the rate of the Eu(S6)→ Eu(C2) transfer. Decay kinetics indicated that even at room temperature the Eu(S6) emission could be further reduced if the dopant content was higher than 10%. Both at room and liquid nitrogen temperatures the decay kinetics of the Eu(C2) emissions are characterized by the time constants of about 1.0 ms for all concentrations, indicating that up to 10% of the dopant content no concentration or thermal quenching takes place. The liquid nitrogen Eu(S6) luminescence is characterized by a time constant of about 7 ms for the 0.2% specimen. At room temperature this value decreases to 5.6 ms.